Immunity 619 



isms should have equal capacity for absorbing complements and 

 amboceptors from blood-serum. (6) The true cholera organism 

 should not be hemolytic. Too much reliance must not be placed 

 upon the agglutination tests alone, as will be made clear by a perusal 

 of the paper upon Bacteriological Diagnosis of Cholera by Ruffer.* 

 (7) The complement fixation test should be position. 



Immumty. — One attack of cholera usually leaves the victim 

 immune from further attacks of the disease. Gruber and Wiener, f 

 Haffkine,t Pawlowsky,§ and Pfeifferjj have immunized animals 

 against toxic substances from cholera cultures and against living 

 cultures. 



Sobernheim** found the Pfeiffer reaction specific against cholera 

 alone, and thought the protection not due to the strongly bactericidal 

 property of the serum, but to its stimulating effect upon the body- 

 cells; for if the serum be heated to 6o°-7o°C., and its bactericidal 

 power thus destroyed, it is still capable of producing immunity. 

 This, of course, is in keeping with our present knowledge of the 

 immune body, which is not destroyed by such temperatures. 



The immunity produced by the injection of the spirilla into 

 guinea-pigs continues in some cases as long as four and a haK months, 

 but the power of the serum to confer immunity is lost much sooner. 



Prophylaxis. — Of the numerous attempts to produce immunity 

 against cholera in man, or to cure cholera when once established 

 in. the human organism, nothing very favorable can be said. Experi- 

 ments in this field are not new. As early as 1885 Ferran, in Spain, 

 administered hypodermic injections of pure virulent cultures of the 

 cholera spirillum, in the hope of bringing about immunity. The 

 work of Haffkine,f t however, is the chief important contribution, and 

 his method seems to be followed by a positive diminution of mortal- 

 ity in protected individuals. Haffkine uses two vaccines — one mild, 

 the other so virulent that it would bring about extensive tissue- 

 necrosis and perhaps death if used alone. His studies embrace 

 more than 40,000 inoculations performed in India. The following 

 extract will show results obtained in 1895: 



" i_. In all those instances where cholera has made a large number of victims — 

 that is to say, where it has spread sufficiently to make it probable that the whole 

 population, inoculated and uninoculated, were equally exposed to the infection — 

 ia all these places the results appeared favorable to inocidation. 



"2. The treatment applied after an epidemic actually breaks out tends to 

 reduce the mortality even during the time which is claimed for producing the 

 full effect of the operation. In the Goya Garl, where weak doses of a relatively 

 weak vaccine had been applied, this reduction was to half the number of deaths; 



*"Brit. Med. Jour.," March 30, 1907, i, p. 735. 



r'Centralbl. f. Bakt.," 1892, xiv, p. 76. 



t"U Bull, med.," 1892, p. 1113, and "Brit. Med. Jour.," 1893, p. 278. 



§ "Deutsche med. Wochenschrift," 1893, No. 22. 

 ^11 "Zeitschrift fiir Hygiene," Bd. xvin and xx. 



* "Zeitschrift fiir Hygiene, xx, p. 438. 



Tt"Le Bull, med.," 1892, p. 1113; "Indian Med. Gazette," 1893, p. 97; "Brit. 

 Med. Jour.," 1893, p. 278. 



